In the manufacturing and/or recycling of various metal parts (e.g., iron, brass, steel, aluminum, copper, alloyed, and the like parts) it is often necessary to clean the parts so that the manufacturing and/or recycling process can proceed or the part (or metal therefrom) can be used for its final intended purpose. Examples of such metal parts include, but are not limited to, machine parts, automotive parts, circuit boards, scrap metal parts, and the like. More specifically, it often become necessary to remove oils, greases, dirt, rolling oils, cutting oils, stamping oils, petroleum products, waxes, and/or other organic compounds or materials from the metal parts. Conventional processes in the past for removing such contaminants have generally involved the use of petroleum based hydrocarbon solvents such as, for example, petroleum distillates, halogenated hydrocarbon solvents, and the like. Although such solvents are generally very effective in removing oils and/or other organic materials, they present significant safety and environmental problems.
In recent years, efforts have been made to develop more environmentally acceptable processes for metal part cleaning--especially processes using aqueous-based cleaning solutions. For example, Williams, U.S. Pat. No. 5,213,624 (May 25, 1993), provided an oil-in-water microemulsion cleaning solution using a terpene solvent, an aliphatic glycol monoether co-solvent, surfactants, and water. Others have prepared various aqueous-based cleaning solutions containing various surfactants which are effective, to at least a limited degree, to remove the organic materials from the parts. Nonetheless, the disposal and/or treatment of the removed organic materials remains a problem. In some cases, the removed organic materials are separated from the water phase and then treated separately.
Even more recently, Ranes, U.S. Pat. No. 5,540,784 (Jul. 30, 1996), disclosed a method of cleaning the interior surfaces of industrial processing equipment (e.g., chemical and oil refinery equipment contaminated during use with oil and solid deposits) using an aqueous cleaning solution containing enzymes and a surfactant. The aqueous cleaning solution was circulated through the equipment under pressure and elevated temperatures (i.e., about 30 to 60 psi and about 220 to 260.degree. F.) to remove the deposits. The enzymes were selected from the group consisting of proteases, amylases, lipases, cellulases, and mixtures thereof. The single surfactant was a long chain dimethyl amine oxide (e.g., lauryl dimethyl amine oxide, stearyl dimethyl amine oxide, myristyl dimethyl amine oxide). The enzymes are reported to help remove the oil deposits from the interior surfaces and then allow the oil and other organic materials to be separated from the aqueous phase and then removed to a waste storage tank.
Various enzymes and/or microorganisms have also been used for waste water or waste sludge treatment. For example, Paquin, U.S. Pat. No. 5,271,845 (Dec. 21, 1993) employed indigenous microorganisms (not otherwise specified) to treat waste sludge containing hydrocarbons. Fredrickson et al., U.S. Pat. No. 5,265,674 (Nov. 30, 1993), employed microorganisms to treat hydrocarbon-contaminated aquifers and other subsurface contaminated areas. Attempts have also been made to use microorganisms to treat oil spills in oceans and other waterways. Enzymes, in combination with various surfactants, have been used extensively in recent years in laundry and washing compositions in order to reduce phosphate loading to the environment. For example, Zaki et al., U.S. Pat. No. 3,676,374 (Jul. 11, 1972), used a proteolytic enzyme in a liquid detergent to assist soil removal.
None of the metal parts cleaning processes of which applicants are aware allow both effective removal of oils and other organic materials and effective degradation of the removed organic materials. It would be desirable, therefore, to provide such a process and compositions for carrying out such a process. It would also be desirable to provide a simplified metal parts cleaning process wherein, not only are oil and other hydrocarbons removed, but they are also degraded to environmentally more acceptable products. The compositions and processes of the present invention provide such metal cleaning compositions and processes.